Sensor system for semiconductor manufacturing apparatus

ABSTRACT

A chamber monitoring system may include a parallel architecture in which a single sensor control system is coupled to a number of different processing chamber control board sensor lines. In an illustrative embodiment, a single rotation sensor such as a tachometer may reside in a central control unit remote from the processing chambers such that rotation data may be processed by a single system and thereafter routed according to a variety of different network communication protocols to the main system controller, a factory interface, or both. In this and other embodiments, pull-up networks in the central control unit and the chamber control boards are matched so as to reduce electrical signal anomalies such as crowbar effects. The central control unit may be programmed via a main system controller to operate according to user defined parameters, which in turn may enable the system to differentiate between certain operating states.

CLAIM OF PRIORITY

This application claims priority under 35 USC §120 as a continuation ofU.S. patent application Ser. No. 12/363,157, filed on Jan. 30, 2009, theentire contents of which are hereby incorporated by reference.

BACKGROUND

In the fabrication of integrated circuits and displays, semiconductor,dielectric, and electrically conducting materials are formed on asubstrate, such as a silicon substrate or a glass substrate. Thematerials, in some examples, can be formed by chemical vapor deposition(CVD), atomic layer deposition (ALD), physical vapor deposition (PVD),ion implantation, plasma or thermal oxidation, and nitridationprocesses. Thereafter, the deposited materials can be etched to formfeatures such as gates, vias, contact holes and interconnect lines. In atypical deposition or etch processes, the substrate is exposed to aplasma in a substrate processing chamber to deposit or etch material onthe substrate surface. Other typical processes that may be performed ona substrate may include thermal processing techniques that may includeRTP, flash lamp, or laser annealing processes.

Physical vapor deposition (PVD), or sputtering, is one of the mostcommonly used processes in fabrication of integrated circuits anddevices. PVD is a plasma process performed in a vacuum chamber where anegatively biased target (typically, a magnetron target) is exposed to aplasma of an inert gas having relatively heavy atoms (e.g., argon (Ar))or a gas mixture comprising such inert gas. Bombardment of the target byions of the inert gas results in ejection of atoms of the targetmaterial. The ejected atoms accumulate as a deposited film on asubstrate placed on a substrate pedestal which generally faces thetarget. During the processes discussed above, the substrate is typicallyheld on a substrate support having a substrate receiving surface. Thesupport can have an embedded electrode that serves as a plasmagenerating device during processing and/or it may also be charged toelectrostatically hold the substrate. The support can also have aresistance heating element to heat the substrate during processing,and/or a water cooling system to cool the substrate or to cool thesupport. One issue that arises is that as device sizes decrease thetolerance to variation across the substrate has become very low suchthat the alignment and positioning of a substrate relative to thesubstrate support, shadow ring, or other chamber components can have anaffect on the uniformity of the process results achieved on thesubstrate. In some cases, one or more regions in a process chamber maybe unable to uniformly generate a plasma (e.g., PECVD, PVD), uniformlydeliver heat to the substrate (e.g., RTP, PECVD), and/or have regions ofnon-uniform gas flow due to the position orientation of the gas inlet orexhaust in the processing chamber, which commonly creates the need torotate the substrate to average out the non-uniformities seen indifferent areas of the processing region of the processing chamber.

SUMMARY

A chamber monitoring system may include a parallel architecture in whicha single sensor control system is coupled to a number of differentprocessing chamber control board sensor lines. In an illustrativeembodiment, a single rotation sensor such as a tachometer may reside ina central control unit remote from the processing chambers such thatrotation data may be processed by a single system and thereafter routedaccording to a variety of different network communication protocols tothe main system controller, a factory interface, or both. In this andother embodiments, pull-up networks in the central control unit and thechamber control boards are matched so as to reduce electrical signalanomalies such as crowbar effects. The central control unit may beprogrammed via a main system controller to operate according to userdefined parameters, which in turn may enable the system to differentiatebetween certain operating states. As an example, the central controlunit may be set with revolutions per minute (RPM) out-of-boundsconditions that permit the system to alert a user that the rotatingapparatus is reciprocating rather than continuously rotating.

DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic sectional view of one embodiment of a PVD chamberhaving a rotatable substrate pedestal.

FIG. 2 is an exemplary system diagram illustrating a processing chambersystem including a processing chamber and a system controller.

FIG. 3 illustrates an exemplary sensor system for monitoring therotation of a substrate support.

FIG. 4 is a circuit diagram illustrating an exemplary chamber monitoringsystem in which a sensor control system may be coupled to a number ofdifferent sensors using a parallel architecture.

FIG. 5 is a system diagram illustrating a sensor control system coupledto multiple processing chambers in a chamber monitoring system.

FIG. 6 illustrates an exemplary hardware configuration of a sensorcontrol system for monitoring multiple processing chambers.

FIGS. 7A and 7B are flow diagrams illustrating an exemplary method forimplementing a digital tachometer monitoring multiple rotating devices.

FIG. 8 is a flow diagram illustrating an exemplary method for processingrotational data associated with multiple rotating devices.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Exemplary Rotating Substrate Support in a Physical Vapor DepositionChamber

FIG. 1 depicts one embodiment of a PVD chamber 100 having a rotatablesubstrate pedestal 126. The PVD chamber 100 generally comprises a lidassembly 102, a main assembly 104, a motion control unit 170, supportsystems 160, and a controller 180. In one embodiment, the lid assembly102 includes a target assembly 110 and an upper enclosure 122. Thetarget assembly 110 includes a rotatable magnetron pack 114 disposedwithin a target base 112 (e.g., water-cooled base), a target 118, and atarget shield 120. The magnetron pack 114 is mechanically coupled to adrive 116 that, in operation, rotates the pack at a pre-determinedangular velocity. One magnetron pack that may be adapted to benefit fromthe invention is described in U.S. Pat. No. 6,641,701, issued Nov. 4,2003 to A. Tepman. The target assembly 110 is electrically coupled to aplasma power supply (not shown), such as an RF, DC, pulsed DC, and thelike power supply.

In one embodiment, the main assembly 104 includes a chamber body 128,the rotatable substrate pedestal 126, an inverted shield 136circumferentially attached to the body 128, and a plurality of radiantheaters 134. The shield 136 generally extends from the upper portion ofthe member body 128 downward and inward toward the pedestal 126. Thesubstrate pedestal 126 includes a substrate platen 154 and a columnmodule 150 that are coupled to one another. Vacuum-tight couplingbetween the lid assembly 102 and the main assembly 104 is illustrativelyprovided by at least one seal, of which an o-ring 132 is shown.

A substrate 130 (e.g., silicon (Si) wafer, and the like) is introducedinto and removed from the PVD chamber 100 through a slit valve 124 inthe chamber body 128. The radiant heaters 134 (e.g., infrared (IR)lamps, and the like) are generally used to pre-heat the substrate 130and/or internal parts of the chamber 100 to a temperature determined bya specific process recipe. As the radiant heaters 134 are positionedbelow the shield 136, the heaters 134 are protected from deposition ofthe sputtered target material that may adversely affect heaterperformance.

In operation, the platen 154 may be selectively disposed in an upperprocessing position (as shown) or in a lower transfer position (shown inphantom). During wafer processing (i.e., sputter deposition), the platen154 is raised to the upper position located at a pre-determined distancefrom the target 118. To receive or release the substrates 130, theplaten 154 is moved to the lower position substantially aligned with theslit valve 124 to facilitate robotic transfer of the substrate.

The platen 154 may include at least one polymer member disposed in anupper substrate supporting surface of the platen 154. The polymer membermay be a suitable plastic or elastomer. In one embodiment, the polymermember is an o-ring disposed in a groove. In operation, friction betweenthe substrate 130 and the o-ring may prevent the wafer from slippingalong a substrate supporting surface 186 of the rotating platen 154.

The platen 154 may include an annular peripheral rim extending upwardfrom the surface and an annular peripheral and upwardly facing trench.The rim may define a substrate receiving pocket in the surface thatprovides additional protection from substrate slippage at higher angularvelocities of the platen 154. In some embodiments, the rim may bechamfered, angled, rounded or otherwise adapted to guide the substrate130 for positioning with a minimal offset from a center of the platen154.

In other embodiments, the platen 154 may comprise a clamp ring, anelectrostatic chuck, embedded substrate heaters, passages for backside(i.e., heat exchange) gas and/or cooling fluid, radio-frequencyelectrodes, and other means known to enhance a PVD process. Coupling tothe respective sources (not shown) of the backside gas, cooling fluid,and electric and radio-frequency power may be accomplished using aconventional means known to those skilled in the art.

Returning to FIG. 1, the motion control unit 170 generally includesbellows 148, a magnetic drive 144, a displacement drive 140, and a liftpins mechanism 138 that are illustratively mounted on a bracket 152attached to the chamber body 128. The bellows 148 provide an extendablevacuum-tight seal for the column module 150 that is rotateably coupled(illustrated with an arrow 156) to a bottom plate 192 of the bellows. Avacuum-tight interface between the bracket 152 and the chamber body 128may be formed using, e.g., one or more o-rings or a crushable copperseal (not shown).

The column module 150 includes a shaft 198 and a plurality of magneticelements 142 disposed proximate to the magnetic drive 144. In operation,the magnetic drive 144 includes a plurality of stators that may beselectively energized to magnetically rotate the magnetic elements 142,thereby rotating column module 150 and the platen 154. In one exemplaryembodiment, the angular velocity of the substrate pedestal 126 isselectively controlled in a range of about 10 to 100 RPM. It iscontemplated that the magnetic drive may be replaced by other motors ordrives suitable for rotating the pedestal.

In operation, the flux of the material sputtered from the target 118 isspatially non-uniform because of variations in the material compositionof the target, accumulation of contaminants (e.g., oxides, nitrides, andthe like) on the target, mechanical misalignments in the lid assembly102, and other factors. During film deposition in the PVD chamber 100,the rotational motion of the substrate pedestal 126 compensates for suchspatial non-uniformity of the flux of the sputtered material anddeposit, on the rotating substrate 130, highly uniform films. Forexample, variation in sputtered material from different regions of thetarget 118 are averaged across substrate 130 as it rotates, thusresulting in high thickness uniformity of the deposited films.

The displacement drive 140 is rigidly coupled to the bottom plate 192 ofthe bellows 148 and, in operation, facilitates moving (illustrated withan arrow 184) the substrate pedestal 126 between the lower (i.e., waferreceiving/releasing) position and the upper (i.e., sputtering) position.The displacement drive 140 may be a pneumatic cylinder, hydrauliccylinder, motor, linear actuation or other device suitable forcontrolling the elevation of the pedestal 126.

The support systems 160 comprise various apparatuses that, collectively,facilitate functioning of the PVD chamber 100. Illustratively, thesupport systems 160 include one or more sputtering power supplies, oneor more vacuum pumps, sources of a sputtering gas and/or gas mixture,control instruments and sensors, and the like known to those skilled inthe art.

The controller 180 comprises a central processing unit (CPU), a memory,and support circuits (none is shown). Via an interface 182, thecontroller 180 is coupled to and controls components of the PVD chamber100, as well as deposition processes performed in the chamber.

Exemplary Processing System Configuration

FIG. 2 is an exemplary system diagram illustrating a processing chambersystem 200 including a processing chamber 202 and a system controller204, interconnected by a chamber interface board 206 and a chamberinterlock board 208.

The system controller 204 is adapted to control the various componentsused to complete the substrate support assembly (e.g., the rotatingassembly 150 as shown in FIG. 1) and the processing chamber 202 (e.g.,the reactor 100 as described in FIG. 1). The system controller 204 isgenerally designed to facilitate the control and automation of theoverall process chamber 202 and typically includes a central processingunit (CPU) 210, a memory 212, and support circuits (or I/O) 214. The CPU210 may be one of any form of computer processors that are used inindustrial settings for controlling various system functions, chamberprocesses and support hardware (e.g., detectors, robots, motors, fluidsources, etc.) and monitor the processes (e.g., substrate supporttemperature, power supply variables, chamber process time, I/O signals,etc.). The memory 212 is connected to the CPU 210, and may be one ormore of a readily available memory, such as random access memory (RAM),read only memory (ROM), floppy disk, hard disk, or any other form ofdigital storage, local or remote. Software instructions and data can becoded and stored within the memory 212 for instructing the CPU 210. Thesupport circuits 214 are also connected to the CPU 210 for supportingthe processor in a conventional manner. The support circuits 214 mayinclude cache, power supplies, clock circuits, input/output circuitry,subsystems, and the like. A program (or computer instructions) readableby the system controller 204 determines which tasks are performable on asubstrate. Preferably, the program is software readable by the systemcontroller 204 that includes code to perform tasks relating tomonitoring, execution and control of the movement, support, positioning,and/or rotation of a substrate along with the various process recipetasks and various chamber process recipe steps being performed in theprocessing chamber 202.

The system controller 204 interfaces with the chamber interlock board208 to control elements of the chamber 202, for example, which maybenefit from safety interlock mechanisms (e.g., relays, hardwareswitches, etc.). For example, the chamber cover release mechanism may beaccessible to the system controller 204 via the chamber interlock board208. Before the cover may be opened, for example, the system controller204 may first halt the processing within the processing chamber 202. Theinterlocks may aid the system controller 204 in verifying that one ormore gas valves are shut, the voltage feed is disabled, etc. beforedisengaging the lock mechanism within the lid of the processing chamber202.

The system controller 204 interfaces with the chamber interface board206 to control elements of the processing chamber 202 which may not beattributed with significant safety concerns. In some implementations,the processing system 200 does not include the chamber interlock board208. In other implementations, the chamber interface board 206 and thechamber interlock board 208 may be designed within a single circuitboard.

Exemplary Sensor System for Monitoring the Rotation of a Single Element

FIG. 3 illustrates an exemplary sensor control system 300 for monitoringthe rotation of a mechanism disposed within a processing chamber. Thesystem 300, for example, may be used to monitor the rotatable substratepedestal 126 or the rotatable magnetron pack 114 as described in FIG. 1.The system 300 includes a sensor 301 which each monitors a rotatingelement 305 (e.g., substrate support, magnetron, etc.) within thechamber 202. The sensor 301, in some examples, may include an opticalsensor, proximity sensor, Hall effect sensor, or other sensing devicecapable of determining the position and/or movement of the rotatingelement 305.

One or more sensor lines connect the sensor 301 to the chamber interlockboard 208. For example, the chamber interlock board 208 may process theoutput of the sensor 301 to determine whether or not to disengage therotation of a substrate support until the lift pins of the substratesupport are in the lowered position or until the substrate support hasbeen lifted into deposition position. In other implementations, thesensor 301 may connect to the chamber interface board 206.

The sensor 301 also connects to a tachometer 307. The tachometer 307,for example, may be implemented with an off-the-shelf tachometer such asthe DX 020 panel tachometer available through Motrona GmbH ofRielasingen, Germany. The tachometer 307 receives signals (e.g., voltagepulses) from the sensor 301 and translates the signals into a voltageoutput, the voltage output levels being associated with the RPM of therotating element 305. For example, the tachometer 307 may time thedistance between pulses received from the sensor 301. In anotherexample, the tachometer 307 may count the number of pulses received fromthe sensor 301 over a period of time.

The signal line of the sensor 301 feeds into a monostable multivibrator302 within the chamber interlock board 208. The monostable multivibrator302, for example, may be included in a safety mechanism which monitorswhether or not the rotating element 305 is revolving. The chamberinterlock board 208 may provide the output of the safety mechanism, forexample, to the system controller 204. The system controller 204 maycheck the output of the safety mechanism to verify that the rotatingelement 305 is not revolving before initiating the next processing stepwithin the processing chamber 202. In some implementations, the chamberinterlock board 208 may only be concerned with whether or not therotational element 305 is in movement, not with the actual speed of therotational element 305.

The monostable multivibrator 302 feeds into an opto-isolator 304. Theopto-isolator 304 may provide protection to a CPU 306 from the signalsreceived by the monostable multivibrator 302. For example, theopto-isolator 304 may buffer the CPU 306 from voltage transients.

The CPU 306 receives a sensor output value from the monostablemultivibrator 302 (e.g., rotation on/off) and may use this informationfor determining whether or not a safety concern exists. In someimplementations, the CPU 306 may provide this information to the systemcontroller 204 which may determine whether or not a safety concernexists.

The tachometer 307 calculates the RPM of the rotating element 305 andoutputs a corresponding voltage level. For example, the tachometer 307may output a voltage level ranging from zero to ten volts, ten voltsbeing indicative of a rotational speed of two hundred RPM. In someimplementations, the tachometer 307 may include a display. For example,an LCD screen attached to the tachometer 307 may provide a user with thecurrent RPM measurement. The tachometer 307 may be mounted on the outersurface of the chamber 202, for example, or in an easily accessiblelocation in the vicinity of the chamber 202 (e.g., on a nearby wall,equipment rack, or other surface).

The tachometer 307 couples to the signal and ground lines of the sensor301 to make use of the sensor readings 301 for determining the RPM speedof the rotating element 305. As described in FIG. 3, the tachometer 307may provide the system controller 3 204 with a voltage output which mapsto an RPM range.

Depending upon the hardware composition of the off-the-shelf tachometer307, however, there may be ground and cross-talk incompatibilityproblems introduced to the system 300. For example, the opto-isolator304 may create galvanic isolation between the CPU 306 and the rest ofthe system 300. The introduction of the tachometer 307 may introduce aground potential issue and cross-talk, which in turn may defeat thegalvanic isolation at the CPU 306.

The signal input of the tachometer 307, for example, may include a +24Volt pull-up network 314. The chamber interlock board 208 may similarlyinclude a +12 Volt pull-up network 308 at the signal input from thesensor 301. When the switch mechanism of the monostable multivibrator302 is in the off position, for example, the signal line of the sensor301 may float between approximately sixteen and eighteen Volts or more.This may cause forward biasing at the monostable multivibrator 302(e.g., a CMOS circuit). If the monostable multivibrator 302 is biasedabove its own input supply (e.g., twelve Volts), it may latch up. Thismay produce a crowbar effect between the plus and minus rails which maycause damage to the chamber interlock board 208.

To defeat the forward biasing of the monostable multivibrator 302, anoptional opto-isolator (not shown) may be introduced to the signal andground sensor lines of the sensor 301 before they enter the chamberinterlock board 208. In addition to or instead of the optionalopto-isolator mentioned above, an optional opto-isolator 312 may beintroduced to the signal and ground input lines of the tachometer 307(which are coupled to the signal and ground sensor lines of the sensor301). For example, the optional opto-isolator 312 can provide isolationand avoid crowbar effects.

The system controller 204 receives the output of the tachometer 307. Thesystem controller 204 may use this information to allow a user tomonitor the rotational speed of the rotating element 305. In someimplementations, the system controller 204 may generate an alarmcondition based upon the output of the tachometer 307. For example, ifthe output voltage received from the tachometer 307 reaches zero, thesystem controller 204 may generate an error indicating that the rotatingelement 305 is no longer in motion. In the system 300, the tachometer307 couples directly to the signal and ground sensor lines of the sensor301.

The system 300 may scale for a multi-chamber processing system (e.g.,the multi-chamber processing system 200 as described in FIG. 2), witheach chamber being monitored by a separate tachometer, each tachometerbeing individually coupled to the system controller 204.

Exemplary Sensor System for Monitoring the Rotation of up to EightElements

FIG. 4 is a circuit diagram illustrating an exemplary chamber monitoringsystem 400 in which a sensor control system 402 may be coupled to anumber of different sensors using a parallel architecture. For example,the sensor control system 402 may monitor two or more sensors which aredisposed in the same or different processing chambers. In someimplementations, the sensor control system 402 may analyze data fromeach individual sensor according to user-specified conditions. Thesensor control system 402, in some implementations, may provide thesensor data and/or any information obtained through analyzing the sensordata to the system controller 204, an interface of a multi-chamberprocessing system, or another computer system.

In the illustrated example, the sensor 301 is connected to the chamberinterlock board 208 in the same manner as described in FIG. 3, exceptthe sensor ground is not extended into the chamber interlock board 208.The signal line extending from the sensor 301 may be a ground-seekingdigital signal. The sensor control system 402 couples to the signal lineand the +12 Volt power line of the sensor 301.

The exemplary sensor control system 402, for example, may accept up toeight optically isolated sensor inputs 404. In some implementations, thenumber of sensor inputs can be scaled, for example to allow inputs fromhundreds of channels. The circuitry involved in the sensor inputs 404 isdescribed in greater detail with respect to FIG. 6. A CPU 406 providestachometer functionality individually for each of the eight sensorinputs 404. For example, up to eight sensors, attached to up to eightprocessing chambers, may connect to the sensor control system 402.

In some implementations, more than one sensor may be disposed within asingle chamber. For example, a particular chamber may have both arotating substrate support and a rotating magnetron (e.g., the rotatablesubstrate pedestal 126 and the rotatable magnetron pack 114 as describedin FIG. 1) being monitored by sensor devices.

Instead of using a single sensor for monitoring a rotating device withina chamber, in some implementations sensor data belonging to the twoseparate sensors may monitored in relation to a single rotating device.The consistency in RPM values between the two sensors may be compared,for example, to determine whether a rotating device is reciprocatingrather than revolving. For example, a user may establish parameterswithin the sensor control system regarding the receipt of data from eachsensor device (e.g., if data from sensor device “A” is not followed bydata from sensor device “B”, or if the RPM value associated with thesensor device “A” is not essentially equal to the RPM value associatedwith the sensor device “B”, assert an error condition).

In some implementations, the number of sensor inputs can be scaled. Forexample, a sensor control system may receive inputs from up to severalthousand channels of sensor inputs. Port expanding chips, for example,can be tied into one or more CPU interrupts (e.g., in a priorityinterrupt handler chain) to channel sensor data into the exemplarysensor control system 402.

In some implementations, the sensor control system 402 may be designedinto the system controller 204. In other implementations, the sensorcontrol system 402 may be implemented as a separate entity from thesystem controller 204. For example, the sensor control system 402 may bemounted on or alongside the system controller 204. The sensor controlsystem 402 may or may not communicate with the system controller 204.

The sensor control system 402 may include a display 408 (e.g., LCDscreen, LED display, etc.) which, for example, may provide the user witha visual representation of the current speed of rotation (in RPM) of therotational elements being monitored by each of the up to eight sensorsconnected to the sensor inputs 404 of the sensor control system 402.Other information may be included within the display 408 including, butnot limited to, an identification of each device (e.g., chamberidentification) being monitored by a sensor, an indication of whether ornot an individual input port of the sensor control system 402 ispresently connected to a sensor, or a warning mechanism if an errorcondition has been detected within one or more of the devices beingmonitored by the sensors coupled to the sensor control system 402.

An error condition, for example, may occur when a rotating elementbecomes stuck. For example, if the rotating element 305 were to begin toreciprocate rather than revolve, the sensor 301 may issue measurementpulses which the sensor control system 402 translates to a very high RPMvalue (e.g., a greater than anticipated RPM value such as 200 RPM or1000 RPM, depending upon the functionality of the monitored rotatingelement). The CPU 406 may recognize the high RPM value as an errorcondition and log an error or otherwise alert the user. In someimplementations, a user may establish out-of-bounds conditions for thefunctionality of one or more monitored devices. For example, a user mayspecify that any rotation measurement below 10 RPM or above 200 RPM iscause for generating an error alert.

In some implementations, a higher maximum RPM value may be achieved byusing a higher frequency CPU clock. For example, if sensor inputs areprocessed by the sensor control system 402 (e.g., received andincremented) at a schedule based upon a multiple of the CPU clockfrequency, a higher frequency clock may provide an opportunity forhigher maximum RPM limits while maintaining the same detectiongranularity.

To alert the user to the present conditions of each of the sensorsconnected to the sensor control system 402, the sensor control system402 may supply information to the user via a set of input/output (I/O)lines 410. The I/O lines 410 may communicate information using a varietyof network communication protocols. In some examples, the I/O lines 410may include a sensor bus line 410 a, a serial I/O line 410 b, and ananalog output line 410 c.

The sensor bus line 410 a may be implemented using a DeviceNet networkbus. DeviceNet is an open protocol maintained by the Open DeviceNetVendor Association for a sensor bus, which allows several devices (e.g.,motors, sensors, heaters, lamps, etc.) in a system (e.g., amulti-chamber processing system) to communicate over a single bus with acontroller (e.g., the system controller 204) that provides commands tothe devices to perform their operations (e.g., activation, deactivation,rotation, etc.) and receives feedback from the devices concerning systemoperation (e.g., wafer position, actual gas flow rate, temperature,etc). The system controller 204, for example, may send commands over theDeviceNet network to control the functions of the individual devices.Another sensor bus networking protocol that may be used in addition toor instead of DeviceNet is Seriplex available from Square D Company ofRaleigh, N.C.

The serial I/O line 410 b may be implemented using a multidrop seriallink. The multidrop serial link, in some examples, may accept up tosixty-three sensor devices daisy-chained on a single serial port. Eachsensor device, for example, may be addressed using a unique deviceidentification value.

In some implementations, standard telephone wire (e.g., RJ-14) may beused to connect individual sensor devices into the multidrop seriallink. Communications between the sensor control system 402 and thedaisy-chained sensor devices, for example, may be implemented usingASCII, ASCII hexadecimal, or standard ASCII control characters.Half-duplex communications between the sensor control system 402 andeach sensor device connected to the multidrop serial link may beinitiated by the sensor control system 402.

The serial I/O line 410 b, for example, may be used to couple the outputof the sensor control system 402 to a multi-chamber processing systemwhich may in turn communicate information between individual processingchambers and the sensor control system 402. In one example, the 200millimeter ENDURA platform available from Applied Materials, Inc. ofSanta Clara, Calif. includes a limited number of communication ports. Ifa user desires communication between individual processing chambers of amulti-chamber Endura 200 mm processing system, the serial I/O line 410 bof the sensor control system 402 may be coupled to the front panel portof the single port computer controller of the multi-chamber Endura 200mm processing system.

The analog output line 410 c may include up to eight individual analogoutput lines, one dedicated to each of the sensor inputs 404.

Information provided to the sensor control system 402 over the I/O lines410 (e.g., from the system controller 204) may include, but is notlimited to, RPM limits for each rotating element (e.g., the range inwhich a rotating element is not in an error condition),activation/deactivation of the monitoring of a particular sensor (e.g.,based upon the steps of the process recipe, whether or not the rotatingelement is supposed to be rotating), or other settings associated witheach sensor (e.g., logging settings, error alert settings, etc.). Insome implementations, the sensor control system 402 is provided withstep changes in the expected RPM value associated with one or moresensors (e.g., due to a processing chamber switching to the next step ofa processing recipe, etc.) and/or quality metrics such as an acceptablerange of the calculated RPM value (e.g., an anticipated RPM value offifty RPM plus or minus two RPM) or other statistical information. Forexample, quality metrics can indicate flutter in readings.

The sensor control system 402 may provide rotation data and, optionally,other information to one or more remote systems connected to the I/Olines 410, in some examples, on a scheduled basis, when an alarmcondition has been recognized, or upon request from the remote system.In some implementations, the output of the sensor control system 402 maybe used by the system controller 3 204 to generate device log entries,error alerts, etc.

FIG. 5 is a system diagram illustrating the sensor control system 402coupled to multiple processing chambers 502 in a chamber monitoringsystem 500. Each processing chamber 502 includes a sensor 504 whichmonitors a rotating element (e.g., substrate support, magnetron, etc.).Each sensor 504 is connected to a chamber interlock board 506 and to thesensor control system 402.

The sensor control system 402 may provide tachometer measurement foreach of the sensors 504. The sensor control system 402, in someimplementations, may count the number of pulses received from eachsensor 504 over a period of time. The number of pulses received per unitof time, for example, may be used to calculate an RPM value.

The sensor control system 402, in some implementations, may contain oneor more banks of counters 508 associated with each sensor 504. Forexample, two 16-bit banks of counters 508 may be provided for eachsensor 504. The sensor control system 402 may increment the firstcounter bank 508 on a set interrupt schedule (e.g., timer) and transferthe present value stored within the first counter bank 508 to the secondcounter bank 508 upon receipt of an input from the sensor 504 (e.g., avoltage pulse equating to a single revolution of a monitored rotatingelement).

For example, the first counter bank 508 may be incremented everythousandth of a second. Using a 16-bit counter, the first counter bank508 may overflow every 6.5535 seconds. When the first counter bank 508overflows, an overflow flag 510 may be set. If no interrupt has beenreceived by the sensor 504 a during this period of time, the sensorcontrol system 402 (e.g., software, firmware, etc.) may determine thatthe rotating element is stopped and output an RPM value of zero. Forexample, for practical purposes, if a rotating element is revolving at aslower rate than 10 RPM, it may be considered to be in an errorcondition (e.g., stalled or slowed). In some implementations, a user mayestablish a minimum RPM value which the sensor control system 402 mayuse to recognize error conditions.

When a pulse is received by the sensor 504 a, for example, the sensorcontrol system 402 may transfer the present value of the first counterbank 508 a to the second counter bank 508 a for the sensor 504 a andreset the first counter bank 508 a. The sensor control system 402 maythen set a valid flag 510 a and (optionally) reset the overflow flag 512a. The sensor control system 402 may process the sampled value storedwithin the second counter bank 508 a to determine the length of timesince the previous pulse was received.

If the first counter bank 508 a has overflowed, the sensor controlsystem 402 may set the overflow flag 512 a, reset the valid flag 510 a,and reset both the first counter bank 508 a and the second counter bank508 a to zero.

During a communications housekeeping routine, the software (or firmware)of the sensor control system 402 may check each valid flag 510,processing the data collected within the second counter bank 508 if thevalid flag is set to true to determine the current RPM value associatedwith each bank of counters 508. The communications housekeeping routinemay provide the processed rotational data to the display 408 and/or oneor more remote systems connected to the sensor control system 402 viathe I/O lines 410 (as shown in FIG. 4). In some implementations, if thehousekeeping routine calculates an RPM value above a threshold value(e.g., 200 RPM), the housekeeping routine may assume that an errorcondition has been detected. The housekeeping routine may includeresetting the valid flag 510 after the data has been processed.

If the communications housekeeping routine finds that the valid flag 510is set to false, the housekeeping routine can update the display 408and/or the I/O lines 410 to broadcast an error condition.

Although the system 500 illustrates a single sensor 504 per chamber 502,in some implementations, more than one sensor 504 may be installedwithin a particular chamber 502. For example, the chamber 502 may haveboth a rotating substrate support and a rotating magnetron which aremonitored by the sensor control system 402. In some implementations,rather than connecting to the chamber interlock boards 506, the sensors504 may be connected to chamber interface boards (e.g., the chamberinterface board 206 as shown in FIG. 2).

FIG. 6 illustrates an exemplary hardware configuration 600 of the sensorcontrol system 402 for monitoring multiple processing chambers. Thehardware configuration 600, for example, may be designed to mitigatevoltage transients and to protect connecting hardware from electricalsignal anomalies within a chamber monitoring system (e.g., the chambermonitoring system 400 as described in FIG. 4).

The sensor control system 402 is configured to receive up to eightoptically isolated sensor inputs 404 (e.g., each connected to a sensorsuch as the sensor 301 of FIG. 3). Each sensor input 404 is comprised ofan authorizer with positive channel and negative channel voltage inputswhich are galvanically isolated up to 1500 Volts. The authorizerincludes forward transistors to ground, ground being internal to theboard and floating as per the overall system (e.g., the system 400 asdescribed in FIG. 4). A five Volt pull-up network feeds into the CPU406. The sensor inputs 404, in some implementations, may drawapproximately one milliamp off of the sensor signal line.

The CPU 406, in some implementations, may be running at approximatelytwelve million instructions per second. The sensor inputs 404 are eachconnected to a direct or vectored interrupt (INTx) 602 on the CPU 406.In some implementations, the INTx 602 may be a negative interrupt.

In some implementations, the sensor inputs 404 may be indirectlyconnected to the INTx interrupts 602. For example, one or more INTxinterrupts 602 may be connected to port expanders which allow theconnection of several sensor lines to a single INTx interrupt 602. Theport expanders, for example, may be implemented using port expander chiphardware/firmware built into the sensor control system 402. In anotherexample, off-the-shelf port expanders may be added to the sensor controlsystem 402 to increase the total number of sensors being monitored bythe sensor control system 402.

The CPU 406 controls the three I/O lines 410. The sensor bus line 410 aincludes a set of buffers 604. The serial I/O line 410 b includes amultidrop serial link logic module 606. The multidrop serial link logicmodule 606 controls the daisy-chaining of the information associatedwith each sensor device sharing the serial I/O line 410 b.

For the analog line 410 c, the CPU 406 presents digital data to a set ofeight digital to analog converters (DACs) 608. The DACs 608 outputanalog signals to the analog output line 410 c. In some implementations,the analog output line 410 c is comprised of eight separate analoglines, each carrying data for a particular sensor attached to the sensorcontrol system 402. The output of the DACs 608, in some implementations,may be adjusted by a set of amplifiers 610. For example, if the DACs 608output a zero to five Volt range, the amplifiers 610 may increase theanalog signal range to zero to ten Volts. The zero to ten Volt range,for example, may map to a zero to two hundred RPM range. In otherimplementations, electrically selected potentiometers may be usedinstead of DACs to provide an analog output signal.

The CPU 406 also may drive a display 408. In some implementations, thedisplay 408 includes an LCD screen which presents information regardingeach of the sensors monitored by the sensor control system 402.

In some implementations, the CPU 406 may receive its input voltage(e.g., 24V DC) from the sensor bus line 410 a or an analog interface.If, however, the serial I/O line 410 b is the only I/O line 410connected to the sensor control system 402, the input power may bederived from a coaxial cable and DC power jack connection. In someimplementations, the sensor control system 402 draws approximately twoWatts of power or less. For example, the sensor control system 402 maydraw approximately one Watt of power.

Exemplary Methods for Monitoring the Rotation of a Processing ChamberDevice

FIGS. 7A and 7B are flow diagrams illustrating exemplary methods forimplementing a digital tachometer monitoring multiple rotating devices.The methods, for example, may be implemented within the sensor controlsystem 402 (e.g., using the software and/ or firmware included withinthe CPU 406). The methods may be implemented individually for eachrotating mechanism monitored by the digital tachometer.

As shown in FIG. 7A, a first method 700 implements a timeout mechanismfor calculating the time between received sensor interrupts. The method700 may additionally be used for determining when a monitored rotationaldevice is not in motion. For example, the sensor control system 402,rather than waiting for an indefinite period of time for an interruptfrom a sensor indicating that a rotating device has completed arevolution, may instead at a predetermined point make the assumptionthat it has taken too long for a single revolution, and therefore therotating device is likely not in motion.

The method 700 begins with receiving a timeout interrupt (702). Thetimeout interrupt, in some implementations, may be a hardware-basedtimeout value. In some implementations, the timing of the timeoutinterrupt may be based upon a multiple of a system clock. For example,the timeout interrupt may be generated by a one kilohertz clock output.In other implementations, another clock output including, but notlimited to, a ten kilohertz or one hundred kilohertz clock output may beused.

Upon receipt of the timeout interrupt, a counter bank is incremented(704). The counter bank, in some implementations, may be sized such thatif incremented at each timeout interrupt, the counter bank may overflowat a timeout value slower than the slowest anticipated RPM value of anymonitored rotating device. For example, using a one kilohertz clock, asixteen-bit counter bank (e.g., the bank of counters 508 as described inFIG. 5) may overflow every 6.5535 seconds. In this example, the slowestanticipated rotational rate may be ten RPM.

If the counter bank has overflowed (706), the overflow flag is set(708). In some implementations, the overflow of the counter bank maytrigger an error alert. For example, a user may be alerted at the sensorcontrol system 402 (e.g., audible and/or visible alert via the display408) or remotely through one or more of the I/O lines 410.

As shown in FIG. 7B, a second method 750 implements an interrupt-driventiming mechanism for determining the rotational speed of a monitoredrotational device. The method 750 begins with receiving an interruptfrom a sensor output (752). The interrupt, for example, may be receivedfrom an attached sensor device at one of the interrupt ports 404 of thesensor control system 402. The interrupt indicates a single revolutionof the monitored rotating device.

If the counter bank has not overflowed (754), the method 750 takes asample count from the counter bank (756). In some implementations, thecounter bank 508, incremented as described within the method 700 in FIG.7A, may be used to calculate the speed of a single revolution of themonitored rotational device. For example, at each sensor interrupt, thenumber of timer interrupts since the previous sensor interrupt may becollected from the bank of counters 508. The sample count may betransferred to a second counter bank (758). For example, the samplecount may be transferred to the sixteen-bit bank of counters 508 (asdescribed in FIG. 5).

A valid flag is set (760), indicating that the second counter bankcontains valid data. The valid flag, for example, may be used by a dataprocessing routine. If the valid flag is set to true, a data processingroutine may use the sample count collected within the second counterbank to calculate the estimated speed of the rotating device. Theoverflow flag is reset (762), indicating that no overflow conditionoccurred during this processing cycle. The main counter bank is reset(764). The method 700, for example, may then continue to collect a countof timer interrupts occurring since the interrupt received in step 752.The method 700 may continue to increment the main counter bank until thenext sensor interrupt is received by the method 752.

If, upon receipt of a sensor interrupt (752) the main counter has beenfound in an overflow condition (754) (e.g., the overflow flag is set totrue), the overflow flag is reset to false (766). The valid flag isreset to false (768), the second counter bank is reset to zero (770),and the main counter bank is reset to zero (772), thus re-initializingall flags and counters.

FIG. 8 is a flow diagram illustrating an exemplary method 800 forprocessing rotational data associated with multiple rotating devices.The method 800, for example, may be used in processing the sample datacollected by the methods 700 and 750, as described in FIGS. 7A and 7B.For example, the method 800 may be implemented within the softwareand/or firmware of the CPU 406 of the sensor control system 402.

The method 800 begins with communications housekeeping (802). Thecommunications housekeeping, for example, may include receiving arequest for information from one or more remote systems (e.g., connectedto the sensor control system 402 by one or more I/O lines 410). In otherexamples, the communications housekeeping may include receiving hardwareinterrupts (e.g., the attachment of one or more sensor devices to theinterrupt ports 404) or software interrupts (e.g., the recognition of anerror condition within the method 700 or 750 as described in FIGS. 7Aand 7B). At some point, the communications housekeeping checks for validdata associated with one or more of the rotating devices monitored bythe sensor control system 402.

If the valid data flag is set to a value of true (804), data associatedwith the valid data flag is processed (806). For example, the datawithin the second counter bank 508 (as described in FIG. 5) may beprocessed to calculate an RPM value associated with the rotating devicebeing monitored.

Using the value calculated through processing the data, the displayinformation is updated (808). For example, the display 408 connected tothe sensor control system 402 may be updated to reflect the RPM valuecalculated. Additionally, one or more data blocks may be formatted fornetwork transmission of the processed data (810). For example, thecalculated RPM value may be transmitted to one or more remote systemsover the I/O lines 410. After having processed the data associated withthe valid flag, the valid flag is reset to false (812). Data may then beprovided to one or more remote systems (816). For example, the user maybe alerted as to the present RPM value of the rotating element via oneor more remote systems.

The method 800 may repeat the process for each rotating device monitoredby the sensor control system 402. If the method 800 finds that the validdata flag associated with a rotating device is set to a value of false(804), the display information may be updated (814) and data may beprovided to one or more remote systems (816) regarding the status of therotating element. For example, the user may be alerted via the display408 and/or one or more remote systems that the rotating element is notin motion.

In some implementations, the method 800 processes data associated witheach monitored sensor before updating the display 408 and/or the remotesystems. For example, the processed data may be collected within a datalog. The data log, for example, may be used to update the display 408upon completion of data processing associated with all monitoredsensors. In some implementations, the processed data may be collectedwithin a data log until a remote system requests the data. Upon request,the communications housekeeping routine may format data blocks withcollected data and transmit the data over the I/O lines 410.

In some implementations, the data may be provided to one or more remotesystems based upon user preferences. For example, if the valid data flagis set to false (e.g., the rotating device has stopped), the informationmay be provided immediately to one or more remote systems. If, instead,the valid data flag is set to true, the information may be collectedwithin a data log and dispatched to the remote system(s) at a later time(e.g., upon request, upon a set batch schedule, etc.).

In some implementations, a user may establish out-of-bounds conditionsand associated alarm mechanisms. For example, if a user has set themaximum speed for a particular rotating device at 120 RPM and the method800 determines a speed of 175 RPM when processing the rotational dataassociated with the rotating device, the method 800 may immediatelyalert one or more remote systems of the out-of-bounds condition.

A number of embodiments have been described. It is contemplated that aplurality of the aforementioned specific features can be combined into asingle device, as will be understood by those skilled in the art.Nevertheless, it will be understood that various modifications may bemade without departing from the spirit and scope of this disclosure.Accordingly, other embodiments are within the scope of the followingclaims.

1. A method comprising: monitoring a rotating element within aprocessing chamber using a sensor; connecting the sensor to a chamberboard through a sensor line; coupling a tachometer to the sensor line;processing rotation data within the tachometer, the rotation dataassociated with the rotating element; and providing the rotation datafrom the central control unit to one or more remote systems.